Automotive safety is concerned with reducing the number of traffic accidents and lessening the severity of injuries when accidents do occur.
Vehicle design gradually improved throughout the history of the automobile industry; higher speeds and heavier traffic, nevertheless, added to a climbing accident rate. In an attempt to deal with the problem, the U.S. Congress passed (1966) a law that permitted the federal government to issue mandatory safety standards for cars, trucks, motorcycles, and other vehicles. Since that time, more than 50 safety standards have been imposed, regulating safety windshields, safety belts, head restraints, brakes, tires, lighting, door strength, and roof strength.
Because of the poor response of the driving public to devices that require their active participation, safety researchers have developed automatic, or passive, restraint systems, which protect occupants without any action on their part. Two basic types of passive restraints have been produced. One, the automatic belt, fastens around the occupant when the car door is closed. The second is the air bag.
In a crash, an air bag--usually one in the steering column and, more recently, one in the fight side of the dashboard--pop out and instantly inflate, forming cushions that prevent the occupants from striking hard surfaces, such as the dashboard or windshield.
It is estimated that about 12,000 lives could be saved and tens of thousands of severe injuries prevented each year if all cars had automatic restraint systems. The U.S. Department of Transportation (DOT) proposed in 1977 that all new cars be equipped with such systems by model year 1984, although major emphasis was on air bags rather than automatic seat belts. Automobile manufacturers objected, principally because the cost of air bags is high: $300 to $1,000 per car, depending on the volume of cars outfitted. New air bag designs have reduced that cost considerably, however, and driver's side air bags have been standard on most cars for several years. Many cars also add one on the passenger side, although they are still in the minority. Millions of older vehicles remain unprotected by air bags.
Until the present invention, if a car owner wishes to have the protection of passenger side air bag there was no practical alternative to purchasing a new car with the dual air bag system. Economically, this is not practical for most people. In the case of some classes or brands of cars, the second air bag is not available at any price.
There are several patents on air bag systems which are independent of the vehicle structure, but they all share severe drawbacks.
Lipkin, U.S. Pat. No. 3,243,822, is typical of the user-worn air bag. The safety device is in the form of a balloon built into a sort of life-vest or jacket, and is manually activated when the user fears a crash is imminent. The balloon stays inflated until the wearer deflates it. There are several problems with this approach. First, if it is nearly impossible to get some people to fasten seat belts, even when every car has been equipped with them since the early 1970's, how likely is it that such people will be willing to don a bulky life vest every time they climb into a car? Even if your passenger might be inclined to wear such a device, how do you protect all of the various people who might ride in your car, if they do not own life vests? Second, and most important, any system which relies on user-activated inflation is not practical. Most automobile collisions occur so fast that there is simply no time to inflate a balloon manually by the time the user realizes that such inflation is required. For that matter, a fully inflated balloon filling the space between the passenger and the dashboard as soon as a passenger feels unsafe could introduce an additional safety hazard for the driver trying to control the car.
Yandle, U.S. Pat. No. 5,162,006, is representative of the second class of air bag devices which have been proposed: those fitting into, or attaching to, the lap/shoulder belts in the car. All of the shoulder belt attached air bags share the additional drawback that they only work if the shoulder belt is worn, which runs counter to the whole intention of passive restraints. Like Lipkin, Yandle depends upon manual activation of the air bag, with the drawbacks mentioned above. Alternatively, Yandle and others of this sort of device allow the trigger to attach to the car seat or body so that if the wearer exceeds a certain degree of forward travel the bag is activated. The impracticality of this approach is obvious--one can envision reaching for the radio dial at high speed and being slapped in the face by an exploding air bag, with predicable results.
Both of the prior art approaches are incompatible with the kind of impact-sensor automatic triggers which are necessary to inflate the air bag quickly enough to do any good. If the air bag is worn by the user, whether on the person or on a belt, it would be easily triggered by user movement or likely to be at an unusable angle when most needed.